1. Install the developer-channel version of Google Chrome
It takes maybe 3-4 minutes, you basically run a small program to indicate your preference. The developer version also gets new features (such as pressing “F11″ to get full-screen mode) way before the beta/stable releases of Chrome.

2. Read the initial documentation
Extensions currently have very Greasemonkey-like functionality: you identify which web pages should be modified, plus JavaScript to be added to those pages. Your plugin has to have a unique identifier. And you have to bundle your extension directory into a “.crx” Chrome Extension file.

3. Try it out
If you’re running the developer version of Chrome, you can install the “hello world” plugin from the extension howto page just by clicking to download the .crx file. Then type “chrome-ui://extensions/” .